Fear always brings out the best in people...

In 1900, San Francisco’s Chinatown was quarantined with barbed wire fences when a Chinese laborer was suspected to have died of Bubonic plague.

While the cause of death was still undetermined, a cordon was placed around Chinatown, and no Chinese American was allowed to leave the area bounded by California, Kearny, Broadway, and Stockton streets. This restricted the freedom of movement of people, some of whom were American citizens. It caused them many hardships, for they had difficulty in obtaining goods and services from people outside Chinatown. There was a shortage of food, and prices increased sharply. Chinese American businessmen faced a loss of income, and workers a loss of wages. After three and a half months, it was found that there were no cases of bubonic plague within Chinatown. This lengthy quarantine of Chinatown was motivated more by racist images of Chinese as carriers of disease than by actual evidence of the presence of bubonic plague. 

Still, at least they didn't accidentally  burn the area to the ground.